PubMed Health⌕ Search

Biomedical subjects

E Alt

Publications and source records attributed to E Alt.

At least 19 recordsLinked to original sources

p-Hydroxyphenylacetaldehyde, the major product of tyrosine oxidation by the activated myeloperoxidase system can act as an antioxidant in LDL.

The oxidative modification of low density lipoprotein (LDL) may play a significant role in atherogenesis. HOCl generated by the myeloperoxidase/H2O2/Cl- system of activated neutrophils may be operative in vivo making LDL atherogenic. Tyrosine has been found to be oxidized by HOCl to p-hydroxyphenylacetaldehyde (p-HA) capable of modifying phospholipid amino groups in LDL. As an amphiphatic phenolic compound, p-HA may have the potential to act as an antioxidant in the lipid phase of LDL. The present results show that (a) tyrosine exerts a protective effect on LDL modification by HOCl, (b) p-HA could act as antioxidant associated with the lipoprotein preventing cell- and transition metal ion-mediated LDL oxidation and (c) p-HA was able to scavenge free radicals.

Acetaldehyde↗

High prevalence of anal squamous intraepithelial lesions and squamous-cell carcinoma in men who have sex with men as seen in a surgical practice.

INTRODUCTION: Anal high-grade squamous intraepithelial lesions are probable invasive anal squamous-cell cancer precursors, and although unproved, treatment of high-grade squamous intraepithelial lesions may prevent progression to anal squamous-cell cancer. Men who have sex with men are often treated for benign anorectal disorders without consideration given to the possibility of concurrent high-grade squamous intraepithelial lesions or anal squamous-cell cancer. We determined the prevalence of anal high-grade squamous intraepithelial lesions and anal squamous-cell cancer in an urban surgical practice of men who have sex with men referred for treatment of anal condyloma and other benign noncondylomatous anal disorders. METHODS: One hundred thirty-one HIV-positive and 69 HIV-negative men who have sex with men referred for surgical treatment of presumed benign anorectal disease were evaluated by anal cytology, high-resolution anoscopy, and biopsy. Anal cytology and histology were reported with a modified Bethesda classification. RESULTS: One hundred fifty-seven patients (79 percent) were referred for condyloma, 4 (2 percent) for anal squamous intraepithelial lesions (anal high-grade squamous intraepithelial lesions) diagnosed by primary care providers, and 39 (19 percent) for other benign anorectal disorders. One hundred forty-three patients (93 percent) had abnormal anal cytology, with 107 (54 percent) having high-grade squamous intraepithelial lesions on cytology. Biopsy results revealed 120 patients (60.0 percent) with high-grade squamous intraepithelial lesions and 5 patients (3 percent) with invasive squamous-cell carcinoma. Four of five men with anal squamous-cell cancer were HIV positive. Fourteen men (36 percent) who have sex with men referred for noncondylomatous benign anal disorders had high-grade squamous intraepithelial lesions, and three (8 percent) had anal squamous-cell cancer. High-grade squamous intraepithelial lesions and anal squamous-cell cancer were seen most often at the squamocolumnar junction. CONCLUSIONS: Men who have sex with men referred for treatment of either condyloma or noncondylomatous benign anorectal disease had a high prevalence of anal high-grade squamous intraepithelial lesions and anal squamous-cell cancer. All men who have sex with men referred for treatment of benign anorectal disease should have high-resolution anoscopy and aggressive biopsy of all abnormal areas. Treatment of external lesions alone could miss high-grade squamous intraepithelial lesions or anal squamous-cell cancer.

Adult↗

Endovascular irradiation from beta-particle-emitting gold stents results in increased neointima formation in a porcine restenosis model.

BACKGROUND: Recent studies have shown that ionizing radiation reduces neointima formation after balloon angioplasty and stent implantation in experimental models of restenosis and first clinical trials. The objective of this study was to determine the dose distribution of a new beta-particle-emitting radioactive gold stent and to evaluate the dose-dependent vascular response in the coronary overstretch pig model. METHODS AND RESULTS: Sixteen Göttinger minipigs underwent placement of 11 nonradioactive and 36 beta-particle-emitting stents with activity levels of 10.4+/-0.6, 14.9+/-2.4, 22.8+/-1.3, 35.8+/-2. 8, and 55.4+/-5.3 microCi of (198)Au. Three months after implantation, the percent area stenosis, neointimal thickness, neointimal area, and vessel injury were analyzed by quantitative histomorphometry. The lifetime radiation doses at a depth of 1 mm were 3.3+/-0.2, 4.7+/-0.5, 7.2+/-0.4, 11.4+/-0.9, and 17.6+/-1.7 Gy for the different activity groups. No dose-response relationship was observed in the radioactive stents with respect to percent area stenosis (P=0.297), mean neointimal thickness (P=0.82), or mean neointimal area (P=0.65). Significantly lower neointima formation and less luminal narrowing was seen in the control group than in the beta-particle-emitting stents (P<0.001). Multilinear regression analysis revealed that only radioactivity made a significant independent contribution to the degree of percent area stenosis (P<0. 001). CONCLUSIONS: Neointima formation in pigs is markedly increased by beta-particle-emitting stents with (198)Au as the radioisotope. This study provides evidence that dosages of 3 to 18 Gy of low-dose-rate beta-particle irradiation via endovascular stents cause pronounced luminal narrowing in the animal model at 3 months.

Animals↗

Inhibition of neointima formation after experimental coronary artery stenting: a new biodegradable stent coating releasing hirudin and the prostacyclin analogue iloprost.

BACKGROUND: To minimize acute stent thrombosis and development of restenosis, stents coated with biodegradable and nonbiodegradable polymers have been proposed to serve as sustained-release drug carriers. METHODS AND RESULTS: In both a sheep and a pig model, we examined the vascular response to standard and high-pressure implantation of coronary Palmaz-Schatz stents coated with a 10-microm layer of polylactic acid (MW 30 kDa) releasing recombinant polyethylene glycol (r-PEG)-hirudin and the prostacyclin analogue iloprost, both drugs with antithrombotic and potentially antiproliferative effects. Study observation time was 28 days. Between the corresponding stent groups, no differences were observed with regard to preplacement and postplacement implantation parameters. The morphometric analysis demonstrated that the coating was associated with a greater lumen diameter through a reduction in the mean restenosis area by 22.9% (P<0.02) in the standard-pressure model (sheep) and by 24.8% (P<0.02) in the overstretch pig model compared with uncoated control stents without inducing a local inflammatory response. CONCLUSIONS: The results from this study demonstrate beneficial effects of a polymeric stent coating with polylactic acid releasing r-PEG-hirudin and iloprost on the development of restenosis after coronary stent placement at 4 weeks, independent of the extent of vascular injury. Future studies are proposed to investigate the integration of other substances to further enhance the potential of the stent coating on reducing neointimal formation.

Absorbable Implants↗

Coronary stent symmetry and vascular injury determine experimental restenosis.

OBJECTIVE: To assess the impact of stent symmetry on restenosis using the coronary overstretch sheep model. METHODS: Neointimal thickness, injury index, and percentage diameter and area stenosis were calculated by digital morphometry. The standard deviation of the angular burden was used to assess stent symmetry for each section. MATERIALS: 15 healthy Merino sheep (63-75 kg) underwent implantation of 30 slotted tube stents (7 mm). Restenosis was induced by calculated overstretch of the coronary artery. Twenty eight days after implantation, stents were excised and underwent histological examination using quantitative digital morphometry. RESULTS: The severity of vessel injury was positively correlated with neointimal thickness and with percentage diameter and area stenosis (p < 0.001). Mean neointimal thickness and mean vascular injury per cross section were strongly related to the standard deviation of angular burden, with correlation coefficients of 0.6 and 0.8, respectively (p < 0.001). CONCLUSIONS: The well known relation between vascular injury and restenosis was confirmed, and a new relation was discovered between stent asymmetry and restenosis. If these results apply to human coronary arteries, restenosis may also be dependent on the degree of asymmetric stent expansion. These results should influence the development of new stent designs to reduce asymmetric stent expansion, leading to a more homogeneous strain distribution in stented coronary segments.

Angioplasty, Balloon, Coronary↗

[Development of a radioligand assay for quantifying specific prostaglandin E1 binding in ischemic ulcers].

Ulcers of the lower extremities are of immense socioeconomical importance. Prevention and therapy of these trophic lesion are hence of great interest. In granulation tissue of ischemic ulcers Laser Doppler flow was previously shown to be higher compared to that in ischemic/adjacent skin or in ulcer without granulation tissue. Intravenous infusion of prostaglandin E1 significantly increased Laser Doppler flow. The present study was designed to test the hypothesis whether the increased baseline and prostaglandin E1-stimulated perfusion of granulation tissue is due to an increased number of prostaglandin E1-receptors in granulation tissue. Therefore, a radioligand binding assay was developed. In an initial pilot study the density of the prostaglandin E1-receptors in granulation tissue of ulcers was compared to that in ischemic/adjacent skin in 8 patients suffering from peripheral arterial occlusive disease requiring debridement or amputation of limbs because of ischemic lesions. The amount of specific binding sites detected was not significantly different between granulation tissue and ischemic/adjacent ulcer tissue. However it cannot be excluded that a possible difference might be detectable with more sensitive assays. In the future we hope to establish a more sensitive assay in order to be able to answer the initial question, whether there is a difference concerning the density of prostaglandin E1 receptor sites in granulation tissue and ischemic/adjacent skin.

Aged↗

Marked reduction in atrial defibrillation thresholds with repeated internal cardioversion.

OBJECTIVES: This study was performed to assess the atrial defibrillation threshold in patients with recurrent atrial fibrillation (AF) using repeated internal cardioversion. BACKGROUND: Previous studies in patients with chronic AF undergoing internal cardioversion have shown this method to be effective and safe. However, current energy requirements might preclude patients with longer-lasting AF from being eligible for an implantable atrial defibrillator. METHODS: Internal shocks were delivered via defibrillation electrodes placed in the right atrium (cathode) and the coronary sinus (anode) or the right atrium (cathode) and the left pulmonary artery. After cardioversion, patients were orally treated with sotalol (mean 189 +/- 63 mg/day). Eighty consecutive patients with chronic AF (mean duration 291 +/- 237 days) underwent internal cardioversion, and sinus rhythm was restored in 74 patients. Eighteen patients underwent repeated internal cardioversion using the same electrode position and shock configuration after recurrence of AF (mean duration 34 +/- 25 days). RESULTS: In these 18 patients, the overall mean defibrillation threshold was 6.67 +/- 3.09 J for the first cardioversion and 3.83 +/- 2.62 J for the second (p = 0.003). Mean lead impedance was 55.6 +/- 5.1 ohms and 57.1 +/- 3.7 ohms, respectively (not significant). For sedation, 6.7 +/- 2.9 mg and 3.9 +/- 2.2 mg midazolam were administered intravenously (p = 0.003), and the pain score (0 = not felt, 10 = intolerable) was 5.1 +/- 1.9 and 2.7 +/- 1.8 (p = 0.001). Uni- and multivariate analyses revealed only the duration of AF before cardioversion to be of relevance, lasting 175 +/- 113 days before the first and 34 +/- 25 days before the second cardioversion in these 18 patients (p = 0.002). CONCLUSIONS: If the duration of AF is reduced, a significant reduction in defibrillation energy requirements for internal cardioversion ensues. This might extend the group of patients eligible for an implantable atrial defibrillator despite relatively high initial defibrillation thresholds.

Adult↗

Influence of balloon pressure during stent placement in native coronary arteries on early and late angiographic and clinical outcome: A randomized evaluation of high-pressure inflation.

BACKGROUND: High-pressure dilatation is considered a better stent placement strategy, but this has not yet been proved by appropriately designed studies. The objective of this randomized trial was to assess the role of high-pressure dilatation in the early and late outcome of patients undergoing coronary stent placement. METHODS AND RESULTS: Consecutive patients with coronary stent placement were randomly assigned to high- (15 to 20 atm, 468 patients) or low- (8 to 13 atm, 466 patients) balloon-pressure dilatation. The primary end point of the study was the event-free survival at 1 year. Secondary end points were the incidence of stent thrombosis at 30 days and angiographic restenosis (>/=50% diameter stenosis) at 6 months. The incidence of stent thrombosis was 1.7% in the high-pressure and 1.9% in the low-pressure group (relative risk 0.89; 95% CI 0.30 to 2.56). During the first 30 days, although there was no significant difference in the incidence of Q-wave myocardial infarction, the incidence of non-Q-wave infarction was 6.4% in the high-pressure and 3.4% in the low-pressure group (relative risk 1. 87; 95% CI 1.02 to 3.42). The restenosis rate was 30.4% in the high-pressure and 31.4% in the low-pressure group (relative risk 0. 97; 95% CI 0.75 to 1.26). Event-free survival at 1 year was not significantly different between the groups, with 78.8% in high-pressure patients and 75.5% in patients assigned to low-pressure dilatation (hazard ratio 0.85; 95% CI 0.65 to 1.11). CONCLUSIONS: The systematic use of high-balloon-pressure inflation (15 to 20 atm) during coronary stent placement is not associated with any significant influence on the 1-year outcome of patients undergoing this intervention.

Aged↗

What is the ideal rate-adaptive sensor for patients with implantable cardioverter defibrillators: lessons from cardiac pacing.

The development of implantable pacemakers in the clinical setting mirrors the implementation of advanced technical possibilities. In the United States, 83% of all pacemakers implanted in 1996 had rate response as a programmable option. A variety of sensors have been proposed and used for rate control. Among today's many concepts, accelerometer-controlled pacing is the most widely used rate-adaptive principle. Although the use of a second sensor is currently of proven benefit for only a limited number of patients, the concept of closed-loop pacing--implementing a negative feedback between pacing rate and the control signal--merits further investigation. This is of special importance in defibrillator patients whose myocardial contractility is generally limited. These patients are most sensitive to pacing rates that are too high for a given metabolic situation. The integration of rate-adaptive pacing into defibrillators is a natural consequence of the technical evolution.

Defibrillators, Implantable↗

Hydrogen peroxide for prevention of bacterial growth on polymer biomaterials.

BACKGROUND: Despite widespread use of potent antibiotics, infections of artificial implants and catheters are of increasing concern. We tested whether local treatment with 3% hydrogen peroxide (H2O2), long known as an inexpensive wound disinfectant, could prevent or reduce bacterial growth on polymer biomaterials. METHODS: Two-centimeter-long pieces of polyurethane and silicone tubing were contaminated with a standardized solution of Staphylococcus epidermidis (10(5)/mL) and then rinsed and wiped with saline (0.9%) solution. Bacterial growth was assessed after incubation at 37 degrees C for 24 hours. Bacterial colonies were compared for the following treatments: wiping only with saline; wiping with 1.5%, 2%, or 3% H2O2; pretreating biomaterials with 3% H2O2 and subsequent contamination for 2 and 4 hours without treatment after contamination; and contamination of tubings 1 month after pretreatment with 3% H2O2. The effect of 3% H2O2 was also assessed on contamination with Escherichia coli. RESULTS: Bacterial growth was reduced by more than 99% when the contaminated tubes were treated with 3% H2O2 compared with saline control (p < 0.001). Lower concentrations of H2O2 were less effective. The length of the contamination period had no influence on the effectiveness of H2O2 when used on polyurethane but did with silicone tubings. Pretreatment with H2O2 1 month before contamination still reduced bacterial growth rate by 90% on polyurethane and by 75% on silicone tubings. Comparable effects on bacterial growth rate were observed for staphylococci (-90%, p < 0.001) and escherichiae (-90%, p < 0.001). CONCLUSIONS: Local treatment with 3% H2O2 significantly reduced bacterial growth on polymer biomaterials even for 1 month after treatment. This finding might influence clinical strategies of prevention of foreign body infection.

Anti-Infective Agents, Local↗

Initial experience with a new balloon-guided single lead catheter for internal cardioversion of atrial fibrillation and dual chamber pacing.

BACKGROUND: Based on the observation that internal cardioversion (IntCV) of atrial fibrillation is effective with electrodes in the right atrium and pulmonary artery, a new balloon-guided catheter and external defibrillation device with optional dual chamber pacing was evaluated. METHODS: IntCV was attempted in 27 patients (age: 57 +/- 10 years, duration: 14 +/- 18 months, left atrial diameter 56 +/- 8 mm) using a new defibrillation device (Alert, EP MedSystems, Inc., NJ, USA) that allows the delivery of biphasic shocks (0.5-15 J, variable tilt), atrial and ventricular pacing, and online signal recording. Pacing and defibrillation shocks were applied via a 7.5 Fr balloon-guided catheter (EP MedSystems, Inc.). Pacing, sensing, and triggering were established through the proximal atrial array and an electrode ring between both defibrillation arrays and a single ventricular electrode ring. Catheters were inserted from the antecubital vein. RESULTS: In 25 of 27 patients sinus rhythm was restored with a mean energy of 6.7 +/- 4.5 J. In five patients, atrial postshock pacing was required for bradycardia and atrial premature beats. The mean fluoroscopy time was 2.0 +/- 1.3 minutes. CONCLUSION: The high success rate, ease of application, and backup dual chamber pacing suggest that this system is an alternative to established methods of cardioversion. In certain indications, such as failure of prior external cardioversion and situations in which a standard pulmonary balloon catheter is needed, this system would be advantageous.

Atrial Fibrillation↗

Antithrombogenic coating of stents using a biodegradable drug delivery technology.

To reduce the thrombogenic properties of coronary artery stents, a biodegradable polylactic acid (PLA) stent coating with an incorporated thrombin inhibitor and a platelet aggregation inhibitor has been developed. In an ex vivo human stasis model, its effect on platelets, plasmatic coagulation and its release characteristics were studied using whole blood. Bare steel and bare gold-surface stents were compared to steel and gold-surface stents coated with PLA (30 kDa) containing 5% polyethyleneglycol (PEG)-hirudin and 1% iloprost, with an empty tube as control. Markers of activated coagulation (prothrombin fragment F1-2 and thrombin-antithrombin III complex, TAT), were assayed and the release of drugs from the coating was assessed by aPTT and collagen-induced platelet aggregation. Bare steel and gold stents were completely covered by a blood clot, and high levels of coagulation markers (F1-2 fragment and TAT) were detected. No differences in the thrombogenic properties were found between bare gold or steel stents. Coated stents were free of blood clots and only minor elevations of markers were detected. Release data from in-vitro studies over 90 days showed a gradual release of the drugs with an initial exponential release characteristic for PEG-hirudin, slow release of iloprost and a 10% degradation of the PLA carrier. This drug releasing biodegradable coating effectively reduced thrombus formation independent of the metallic surface.

Antithrombins↗

Effect of glycoprotein IIb/IIIa receptor blockade on recovery of coronary flow and left ventricular function after the placement of coronary-artery stents in acute myocardial infarction.

BACKGROUND: Apart from its established effects on vessel patency after percutaneous coronary revascularization, glycoprotein IIb/IIIa receptor blockade by abciximab may improve myocardial perfusion by inhibition of the interaction of platelets and platelet aggregates with the microvasculature. We investigated the effect of abciximab with stent placement in acute myocardial infarction. METHODS AND RESULTS: In a prospective randomized trial, patients undergoing stenting in acute myocardial infarction within 48 hours after onset of symptoms were randomly assigned to receive either standard-dose heparin or abciximab plus low-dose heparin. Immediately after the procedure and at 14-day angiographic follow-up, we assessed flow velocity in the recanalized vessel with the Doppler wire and regional wall motion by the centerline method. End points were changes in papaverine-induced peak flow velocities and in wall motion indices. We assigned 98 patients to standard heparin and 102 to abciximab. We obtained 152 paired flow measurements and 151 paired left ventricular function studies. Residual stenoses of the treated lesions did not differ between the 2 groups. Improvement of peak flow velocity (mean [95% CI]: 18.1 cm/s [13.6 to 22.6 cm/s], n=80, versus 10.4 cm/s [5.4 to 15.4 cm/s], n=72, P=0.024) and wall motion index (0.44 SD/chord [0.29 to 0.59 SD/chord], n=79 versus 0. 15 SD/chord [0.00 to 0.30 SD/chord], n=72, P=0.007) was significantly greater in patients assigned to abciximab than in those on heparin alone. At follow-up, the abciximab group had a higher global left ventricular ejection fraction than the heparin group (62% [59% to 65%] versus 56% [53% to 59%], P=0.003). CONCLUSIONS: Abciximab had important effects beyond the maintenance of large-vessel patency. It improved the recovery of microvascular perfusion and concomitantly enhanced the recovery of contractile function in the area at risk.

Abciximab↗

Unexpected recurrence of sinus rhythm in chronic atrial fibrillation due to sick sinus disease.

A 60-years old patient with symptomatic sick sinus disease was implanted a dual-chamber pacemaker that did well during the following 13 years. Thereafter, the pacemaker had to be explanted because of a systemic infection, with the patient in constant chronic atrial fibrillation in the meantime. After another asymptomatic year, 6 arrhythmogenic syncopes occurred, apparently due to pre-automatic pauses prior to spontaneous conversions to sinus rhythm. Subsequently, the patient was implanted a VVI pacemaker, whereupon he did well henceforth. This case demonstrates the possibility of recurrence of sinus rhythm even after long-standing chronic atrial fibrillation.

Arrhythmia, Sinus↗

A comparative study of activity and dual sensor: activity and minute ventilation pacing responses to ascending and descending stairs.

Previous studies with activity-based rate adaptive pacemakers have shown a somewhat paradoxical response when comparing ascending stairs to descending stairs. The objective of this investigation was to measure dual-sensor rate response provided by activity and minute ventilation (MV) compared with activity alone, and with a control group, during ascending and descending stairs. For dual sensor mode, measured mean peak pacing rate with 72 (92) steps per minute was 111 +/- 13 beats/min (124 +/- 14 beats/min) ascending stairs and 81 +/- 7 beats/min (97 +/- 13 beats/min) for descending. For activity mode alone, mean peak pacing rate was 90 +/- 12 beats/min (108 +/- 19 beats/min) ascending stairs and 97 +/- 12 beats/min (123 +/- 17 beats/min) descending. The mean peak control group heart rate ascending stairs for a step rate of 72 (92) steps/min were 116 +/- 11 beats/min (127 +/- 14 beats/min) ascending stairs and for descending 89 +/- 12 beats/min (95 +/- 11 beats/min). While for dual sensor controlled pacing there was a significant difference for ascending and descending stairs at both step rates, there was no difference between going upstairs and downstairs for activity mode alone. Rates with dual sensor did not significantly differ from respective rates of the control group. The mean correlation coefficient between MV and paced rate was 0.85. Pacing heart rates delivered by the dual sensor mode were appropriate for ascending and descending stairs. In contrast to activity mode alone, the peak heart rates for dual sensor mode are higher during ascending than during descending stairs.

Aged↗

New ICD-technologies: first clinical experience with dual-chamber sensing for differentiation of supraventricular tachyarrhythmias.

Inappropriate ICD therapy for supraventricular arrhythmias remains an unsolved problem and may lead to serious clinical situations. Current algorithms for differentiation of supraventricular and ventricular arrhythmias are based on ventricular sensing solely and, therefore, lack sensitivity and specificity. This preliminary analysis from a multicenter trial comprises data from the first 26 patients who received a Res-Q Micron active-can ICD (Sulzer Intermedics) with a ventricular defibrillation lead and an additional bipolar lead for atrial sensing. Digitized atrial and ventricular waveform storage as well as interval charts from 102 induced and 30 spontaneous arrhythmia episodes were prospectively collected and analyzed with regard to appropriateness of ICD therapy. From all 132 arrhythmia episodes, high-quality stored dual-chamber intracardiac electrograms (IEGM) could be retrieved for further analysis: in 40 (30%) episodes, atrial fibrillation (AF with rapid ventricular response 22, AF with VT 9, AF with VF 9) was identified as the underlying intrinsic rhythm, and inappropriate ICD therapy was delivered in 4/22 (18%) episodes of AF with rapid ventricular response. In the remaining 92 (70%) episodes, sinus rhythm was the underlying atrial rhythm (SR with VT 13, SR with VF 79), and no inappropriate therapy was observed. Three of 22 (15%) high-energy shocks delivered for ventricular arrhythmias (VT 9, VF 9, rapid AF 4) terminated AF at the same time. In total, there were 3 complications (2 atrial lead dislodgments, 1 revision for bleeding). Both atrial lead dislodgments occurred in the 2 patients with passive-fixation leads compared to none in the 24 patients with active-fixation leads (p = 0.003). In conclusion, dual-chamber sensing and waveform storage of the new Res-Q Micron offer very helpful diagnostic tools for the detection of inappropriate ICD-therapy. Placement of an additional atrial lead is safe and does not interfere with proper ICD function. However, for avoidance of atrial lead dislodgment, active fixation leads are recommended. With the tested active-can lead configuration, the efficacy of successful atrial cardioversion by high-energy shocks delivered for ventricular arrhythmias seems to be low.

Algorithms↗